&GAS: MIX
The fraction of the mixture taken up by the gas.
The fractions do not necessarily have to add up to 1.
[Each fraction is 0 by default.]
The lowest electron energy in the cross section, energy loss,
mean free path and F0 plots. This parameter has no impact on
the drift velocity and diffusion calculations.
[By default 0.01 eV.]
The largest electron energy which is considered during the
computations of F0, the drift velocity and the diffusion.
This is also the largest electron energy shown in the
cross section, energy loss, mean free path and F0 plots.
This parameter should be chosen sufficiently large, otherwise
the program might not be able to detect ionisation.
The adverse effect of choosing this parameter too large
is an increased CPU time consumption.
[By default 25 eV.]
The largest step size allowed during integration.
One should keep in mind that integration in each step is done
using a 6-point Gauss technique and that the steps never
bridge a change-over between two parametrisations.
[By default 0.5 eV.]
Garfield warns if the fraction of F0 fraction above the first
ionisation potential of any of the gas components exceeds
the value of this parameter.
[By default 0.01.]
The range of E/p. There is usually no problem with the
computations for small E/p, but at high E/p one may hit
the ionisation potential of one of the gas components.
[By default 0.5 to 50.]
Number of points in the drift velocity and diffusion tables.
[By default 20.]
Selects whether the spacing of the E/p points should be linear
or logarithmical.
[Logarithmic by default.]
Requests a plot of F0 for each E/p. This plot is useful when
you wish to see which electron energies play a role.
The curve is plotted using polyline representation FUNCTION-1
if ionisation and excitation are not expected to be a problem,
using representation FUNCTION-2 if a significant fraction of
the energy distribution exceeds the first ionisation or
excitation threshold.
[This plot is made by default.]
Requests a plot of the fraction of energy lost by an electron
during collisions with the gas molecules / atoms.
The curve is plotted using polyline representation FUNCTION-1.
[This plot is by default not made.]
Requests a plot of the elastic electron scattering cross section.
The curve is plotted using polyline representation FUNCTION-1.
[This plot is made by default.]
Requests a plot of the mean free path of electrons in the gas.
The curve is plotted using polyline representation FUNCTION-1.
[This plot is by default not made.]
Requests that the information contained in the 3 kinds of plots
described before (energy loss, cross section, mean free path)
be printed.
[This table is by default not printed.]
MIX only computes the drift velocity and longitudinal diffusion
for electrons, not for ions. This keyword enables adding an ion
mobility to the tables.
This format only allows for mobilities that are constant or depend
in a simple way on E/p. In the latter case, the argument of MOBILITY
should be a function with EP as variable.
Since the ion mobility is usually constant or nearly so, this should
be adequate, please contact the author if this proves a limitation.
The Garfield unit for mobility is cm2/V.microsec.
[By default: no mobility.]
MIX only computes only drift velocity and the longitudinal diffusion
for electrons in the gas mixture. It does not compute the Townsend or
attachment coefficient. This keyword enables adding the Townsend
coefficient to the tables.
This format only allows for Townsend coefficients that depend in a
simple way on E/p. The argument of TOWNSEND-COEFFICIENT should be a
function with EP as variable.
Since the MIX instruction is only meant to provide an approximate
table, the limitation to parametrisations should not be a severe
limitation. MAGBOLTZ should be used if more accuracy is desired.
The Townsend coefficient should be entered as alpha/pressure, with
alpha in units 1/cm and the pressure in Torr.
[By default: no Townsend coefficient.]
MIX only computes only drift velocity and the longitudinal diffusion
for electrons in the gas mixture. It does not compute the Townsend or
attachment coefficient. This keyword enables adding the attachment
coefficient to the tables.
This format only allows for attachment coefficients that depend in
a simple way on E/p. The argument of ATTACHMENT-COEFFICIENT should be
a function with EP as variable.
Since the MIX instruction is only meant to provide an approximate
table, the limitation to parametrisations should not be a severe
limitation. MAGBOLTZ should be used if more accuracy is desired.
The attachment coefficient should be entered as beta/pressure, with
beta in units 1/cm and the pressure in Torr.
[By default: no attachment coefficient.]
Keyword index.
Formatted on 10/11/98.